In sea-going ships, hold capacity is of great importance, and loading and unloading time is of equal importance. The unloading problem arises due to the fact that the storage facilities on shore are located remotely from the dock, and the usual gravity dump tanks, in such instance, are of no use. The object of the invention here referred to is to disclose a tank that will hold a maximum load and that will be provided with slope sheets and aerating means and with pressure equalization on both sides of the slope sheets to prevent damage thereto, as well as a method of handling pulverulent material to provide easy, quick loading and unloading, without contamination of the environment, or the product.